The relatedChildren have custom fields / columns and I need them to be accessible (hence the ChildPageType necessity).

I've looked into the documentation found at: [http://devnet.kentico.com/articles/kentico-8-technology-documentquery-api] and the forums: [https://devnet.kentico.com/forums/f58/fp3/t29998/retrieving-data-from-the-database], but I am not able to get the above into one (1) query.